From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4C6BC4CECE for ; Mon, 14 Oct 2019 19:29:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AEBAE21721 for ; Mon, 14 Oct 2019 19:29:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388871AbfJNT3y (ORCPT ); Mon, 14 Oct 2019 15:29:54 -0400 Received: from relay9-d.mail.gandi.net ([217.70.183.199]:46625 "EHLO relay9-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730405AbfJNT3y (ORCPT ); Mon, 14 Oct 2019 15:29:54 -0400 X-Originating-IP: 90.76.216.45 Received: from windsurf.home (lfbn-1-2159-45.w90-76.abo.wanadoo.fr [90.76.216.45]) (Authenticated sender: thomas.petazzoni@bootlin.com) by relay9-d.mail.gandi.net (Postfix) with ESMTPSA id CA804FF808; Mon, 14 Oct 2019 19:29:39 +0000 (UTC) Date: Mon, 14 Oct 2019 21:29:38 +0200 From: Thomas Petazzoni To: Remi Pommarel Cc: Lorenzo Pieralisi , Bjorn Helgaas , Ellie Reeves , linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] PCI: aardvark: Wait for endpoint to be ready before training link Message-ID: <20191014212938.14516102@windsurf.home> In-Reply-To: <20190522213351.21366-2-repk@triplefau.lt> References: <20190522213351.21366-2-repk@triplefau.lt> Organization: Bootlin X-Mailer: Claws Mail 3.17.4git47 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Remi, On Wed, 22 May 2019 23:33:50 +0200 Remi Pommarel wrote: > When configuring pcie reset pin from gpio (e.g. initially set by > u-boot) to pcie function this pin goes low for a brief moment > asserting the PERST# signal. Thus connected device enters fundamental > reset process and link configuration can only begin after a minimal > 100ms delay (see [1]). > > Because the pin configuration comes from the "default" pinctrl it is > implicitly configured before the probe callback is called: > > driver_probe_device() > really_probe() > ... > pinctrl_bind_pins() /* Here pin goes from gpio to PCIE reset > function and PERST# is asserted */ > ... > drv->probe() > > [1] "PCI Express Base Specification", REV. 4.0 > PCI Express, February 19 2014, 6.6.1 Conventional Reset > > Signed-off-by: Remi Pommarel It is always a bit annoying to add another 100ms in the boot path, but I don't see an easy alternative solution, so: Acked-by: Thomas Petazzoni Thomas -- Thomas Petazzoni, CTO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com